Magnetism influenced by structural disorder in melt-spun DyMn6 − xn Ge6 − xn Fen xn Aln xn (x = 2.5, 3)

摘要

Different chemical and/or geometrical orders were found in melt-spun DyMn6 − x Ge6 − x Fe x Al x with x = 2.5 and 3 having fully amorphous and mixed (crystalline and amorphous) structure, respectively. Thermal variations in magnetization M from liquid helium up to room temperature for both samples are similar. Magnetization value at zero field cooled curve reaches about 0.1μB per formula unit at 2K and then increases. Two maxima are visible, the first at 50K (a sharp effect) and the second very broad ranging from 150 to 200K. 57Fe Mössbauer spectrometry investigation revealed a remaining magnetic component in addition to a prevailing quadrupolar feature. Application of a weak external magnetic field causes an increase in the mean hyperfine magnetic field B hyp and the volume fraction of magnetic component. This observation was confirmed by results of M(T), M(H) and AC magnetic susceptibility measurements. In short-range ordered crystallographic zones characteristic of melt-spun DyMn6 − x Ge6 − x Fe x Al x (x = 2.5, 3) alloys, the related magnetic ordering, called the mictomagnetism or the cluster spin glass appears.